<html>
<body>
    <form action="" method="GET">
        <label>Total</label>
        <input name="number_post" value="10" /><br />
        <label>character one row</label>
        <input  name="post_onrow" value="2"/><br />
        <label>Character </label>
        <input  name="character" value="A"/><br />
        <input type="submit" />
    </form>
    <?php 
        $number_post = $_GET['number_post'];
        $post_onrow = $_GET['post_onrow'];
        $char = $_GET['character'];
        $arr = array();
        for($i=0;$i<$number_post;$i++)
        {
            array_push($arr,$char);
        }
        if($number_post && $post_onrow && $char)
        {
            
            echo '<div style="border:1px solid red;width:300px">';
            foreach ($arr as $k=>$v) {
                
                if($k % $post_onrow == 0)
                {
                    echo '<br/>';
                }
                    
                echo $v;
            }
            echo '</div>';
        }
    
    ?>
</body>
</html>